term1 Definition1term2 Definition2term3 Definition3
Please sign in to your Google account to access your documents:
Contrast nervous and endocrine systems in terms of speed and duration of response.
The nervous system has a fast response and short duration. The endocrine system has a slower response and longer duration.
Differentiate between endocrine and exocrine glands.
Exocrine glands secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ or to the outer surface of the body. Endocrine glands secrete hormones into interstitial fluid and blood.
To what must a hormone bind to cause its effects?
Hormones bind to receptors on target cells.
Explain the process by which hormone receptor numbers are regulated.
When there is a high level of circulating hormone receptor number decreases which is down regulation. This makes the target cell less sensitive to the hormone. When there is a low level of circulating hormone the receptor number increases which is up regulation making the target cell more sensitive to the hormone.
List the two broad classes of hormones giving examples of each.
The two broad classes of hormones are those that are soluble in lipids and those that are soluble in water. The lipid-soluble hormones are steroid hormones, thyroid hormones and nitric oxide. The water soluble hormones are amine hormones (melatonin), peptide hormones (ADH, oxytocin), protein hormones (hGH, insulin).
Describe the action of lipid soluble hormones.
Their mechanism of action is as follows: 1. A lipid-soluble hormone molecule detaches from its transport protein in the bloodstream then crosses the plasma membrane. 2. It binds to receptors located in the target cell. 3. It alters gene expression. 4. mRNA directs synthesis of a new protein which alters the cell's activity.
Describe the mechanism of action of water soluble hormones.
The action of water soluble hormones is: 1. A water soluble hormone (the first messenger) diffuses from the blood. 2. It binds to its receptor on the target cell's plasma membrane. 3. It causes ATP to be converted to cyclic AMP by adenylate cyclase enzyme. 3. Cyclic AMP (the second messenger) activates several enzymes that alters cell activity.
How is cyclic AMP formed? Why is cyclic AMP considered a 'second messenger'?
Cyclic-AMP is formed from ATP by adenylate cyclase. Cyclic-AMP is termed the second messenger. Cyclic-AMP activates otherwise inactive enzymes in the cell to cause the response attributed to the hormone.
List three factors that determine the responsiveness of target cells to a hormone.
The responsiveness of a target cell to a hormone depends on 1. the hormone's concentration in the blood. 2. the number of target cell receptors and 3. influences of other hormones.
What is meant by permissive, synergistic and antagonistic effects of hormones?
Permissive is when the action of the hormone requires a simultaneous or recent exposure to a second hormone to exert its full effect. Synergistic is when more than one hormone produces the same effect and their combined effects are greater than the sum of the two hormones acting alone. Antagonistic is when the action of one hormone opposes the action of a second hormone.
Need help typing ? See our FAQ (opens in new window)
Please sign in to create this set. We'll bring you back here when you are done.
Discard Changes Sign in
Please sign in to add to folders.
Sign in
Don't have an account? Sign Up »
You have created 2 folders. Please upgrade to Cram Premium to create hundreds of folders!